Sewing machine



'June 19, 1951 *Filed Aug. 24, 1945 BLA. SCHMITT SEWING MACHINE 4 She`eLbs-Sheet 1 IN VEN TOR.

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Jul@ 19,1951 y 14mm v 2,557,844-

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June 19', 1951 B. A. SCHMITT t 2,557,844'

d SEWING MACHINE Filed Aug. 24, 1945 y 4 sheets-shed s Patented June 19, 1951 UNITED STATES ATENT OFFICE A. This invention relates to certain new and useful improvements in sewing machines. The invention has particular reference to domestic sewing machines. In this View of the invention, it is the principal object to provide a sewing machine which may be operated with expedience and which is of a construction economical in manufacture as well as highly eicient in use.

It is also an object of this present invention to improve the quality of the sewing produced by a lock-stitch mechanism by providing in the sewing machine a stitch-forming mechanism which requires no oiling or other lubrication for efficient operation, thereby reducing to a minimum, if not entirely eliminating, soiling of the thread and consequently the material being operated upon, as results in sewing machines wherein the stitch-forming mechanism requires lubrication.

In sewing machines, whether for domestic or l industrial use, it is a known fact that the thread, in passing into operative reception and in being cast in the stitch-forming operation, will dispense a certain amount of lint or thread-borne parts, which, if permitted to mix with oil, will lind lodgement upon or within the operative parts of the stitch-forming mechanism and will eventually cause undue wearing of these parts, with the ultimate effect of jamming them against proper operation. Well knowing this disagreeable result in domestic as well as industrial sewing machines, it is a further and equally important object of the invention to provide a simple arrangement for preventing this collection of lint or threadborne parts and the jamming of the same in or 1 upon the operative parts of the stitch-forming mechanism, it being pointed out that the dry lint will be thrown out and away from the stitchforming mechanism by the centrifugal action of such mechanism.

Yet another and equally important object of the invention is the simplicity of assembly between the loop taker and a stationary bobbin case carrier, the loop taker being carried by a vertically positioned shaft disposed to the right of the needle axis, resulting in a structure affording easy and expeditious access to the bobbin case carrier.

Other objects will appear hereinafter.

The invention consists in the novel combination and arrangement of parts to be hereinafter described and claimed.

The invention will be best understood by reference to the accompanying drawings showing the preferred form of construction, and in which:

Fig. 1 is a perspective view of a sewing machine showing my improved mechanismv associated therewith;

Fig. 2 is a perspective View of the stitch-forming mechanism embodied in my invention;

Fig. 3 is a perspective view of a bobbin;

Fig. 4 is a perspective view of a bobbin housing;

Fig. 5 is a perspective View of the bobbin case carrier;

Fig. 6 is a perspective view of the loop taker or hook;

Fig. '7 is a plan View of the loop-forming mechanism embodied in the invention;

Fig. 8 is a plan view of the loop taker or hook embodied in the invention;

Fig. 9 is a plan View of the bobbin case carrier showing the same engaged with its retaining bar;

Fig. 10 is a sectional detail View taken substantially on line lll-l0 of Fig. '7;

Fig. 11 is a plan View of the underside of the loop taker or hook; v

Fig. 12 is a sectional detail View similar to Fig. 10 but showing a slightly modied form of construction;

Figs. 13 to 15 inclusive are schematic views showing the relationship of the needle thread with respect to the loop taker or hook.

The drawings illustrate the preferred form of construction by which the several objects of the invention are accomplished.

Fig. 1 of the drawings illustrates a conventional sewing machine 20 with which my improved stitch-forming mechanism 2| is associated.

In connection with the illustration of Fig. 1, only so much of the sewing machine is referred to as is essential to a clear understanding of the present invention. In this connection, 22 indicates the needle carrying bar, the needle being indicated at 23 and may be of any of the conventional designs. The machine also includes the presser foot bar 24 carrying the presser foot 25, adjustable relative to the feed dog 2B in the usual and conventional manner, the dog being associated with the throat plate 21 adjacent the bedl slide 28 carried by the bed plate 28. The

usual balance wheel 25' is shown as a part of the. mechanical equipment of the sewing machine il.

lustrated at 20, in which sewing machine there is also included the stitch-lengthening or shortening mechanism 26', said stitch-lengthening or shortening mechanism comprising no part of the present invention, being more clearly shown and detailed in my application filed in the United States Patent Office on August 6, '1945, and bearing Serial No. 609,115 and which has matured into Patent No. 2,532,790, December 5, 1950.

My improved stitch-forming mechanism includes, as shown preferably in Figs. 3 to 1l inelusive, a vertically rotatable hook-driving shaft 29 operated in a manner well known in connection with the sewing machine art. This hookdriving shaft is disposed in a vertical plane with the end portion thereof secured by means of a suitable set screw 39 in the sleeve 3l of a loop taker or hook 32. This loop taker or hook is preferably formed substantially cup-shaped, of relatively shallow depth, to provide the vertical wall 33. This wall 33 has formed on its inner surface 34 an internal flange 35, which provides, together with a segmental ring 39, a race 31 for the ange 38 of a bobbin case carrier 39. The loop taker includes a beak 49 which in plan view extends with its point 4l outside of the outside diameter of the hook 32. The beak lll has a downwardly and outwardly tapered edge 42 which terminates into a thread guide 43. To complete this hook, there is provided a thread guard M (Fig. 6) disposed adjacent the beak 49 and provided with a horizontally disposed connecting lip 95 engageaole in a radially extending groove 46 formed in the hook. The thread guard comprises a relatively flat plate, with one end 41 thereof attached to the hook as at 43 by means of a screw or other like connecting element. The opposite end portion of the guard has an inturned lip Q9 engaging in a groove 59 formed in the vertical wall of the hook.

The hook is shown in perspective in Fig. 6 and is adapted to receive the bobbin case carrier 39 in the manner illustrated in Fig. 10. This bobbin case carrier 39 is retained upon the hook with its guiding flange 38 conned in the race 31 by means of the ring 36 having a thread cutting edge I. horizontal flange 52 formed as an integral part of a vertical wall 53. At opposite predetermined points with respect to the wall 53, retaining lips 54 are struck inwardly from this wall for` engagement in retaining grooves 55 formed in the walls 33 of the hook 32. To complete this confinement of the bobbin case carrier 39 within the hook 32, there are secured as at 56 to the hook 32, retaining fingers 51 preferably of resilient material and having their end portions 58 projected through slots 59 formed in the walls 53, the confronting end portions of the fingers 51 being fitted into notches 53 formed in the sleeve 3l.

The bobbin case carrier includes an upper casting ange 69 extending from` the outside diameter of the flange 38 and a lower casting flange 6! extending from the inside diameter as at 38', of the flange 38. This arrangement affords making a relatively small bobbin case carrier diameter to accommodate a large size bobbin. The bobbin case carrier 39 provides a spider-shaped bottom wall 62 from which extends a bobbin shaft 63. There is formed as an integral part of this bobbin case carrier 39 a retaining arm 64 adapted to engage in a notch 65 formed in a bar 66 supported in any suitable manner from the bed plate 28' and having a needle-receiving recess 61.

To complete the bobbin case carrier, there are provided finger notches 63 which facilitate removal of the bobbin from position within the bobbin case carrier 39. A bobbin housing 69 is inthe form of a ring having a bobbin-receiving thread slot 19 formed in a wall 1l thereof and a bobbin thread-receiving notch 12 formed in the wall 1| adjacent the slot 10. This wall 1i also The edge 5| (Figs. 2, '1 and 10) comprises a provides finger notches 13 to facilitate removal of the bobbin 14 therefrom. A tension spring 15 for the bobbin thread is provided, and this spring 15 has its end portions 16 bent for projection through suitable slots 11 formed in the wall 1|. The tension of spring 15 is varied by an adjustment screw 15', and the wall into which this adjustment screw 15 is threaded is of a thickness substantially greater than that of the opposite wall portion of the ring 69, whereby to provide substantial body for the adjustment screw.

The bobbin 14 includes the side walls 18 spaced from each other by a sleeve 19 upon which the bobbin thread is wound.

In Fig. l2, a modified form of construction is shown, and this modified form of construction resides principally in the manner of mounting the hook 32 upon the shaft 29. In this instance, the shaft 29 is provided with a disc 29' at its up per end portion, and this disc in turn is connected by means of suitable connecting screws or other elements 39 to the bottom wall 3l' of the hook The structure illustrated in Fig. 12 is otherwise similar to that shown in Fig. 10. and similar parts are indicated by similar reference characters.

In the normal operation of the loop-forming mechanism constituting my invention, the bobbin' with a roll of bobbin thread thereon is placed in the bobbin housing illustrated in Fig. 4, with the end of the bobbin thread led throughthe slot 10, beneath the tension spring 15 and then led back through the notch 12, with the bobbin thread end passed through the point of juncture between the bed slide plates 23 adjacent the needle 23.

The bobbin with the thread thereon is placed in the bobbin housing xedly secured in any suitable manner to the bobbin case carrier 39, with the shaft 63 projecting through the bobbin sleeve 19. The needle thread is led through the needle eye in the usual manner. The resulting assembly is shown in Fig. 2, and the machine is now ready for operation.

In this connection (reference being had particularly to Figs. 13 to 15 inclusive), in the initial rotation of the hook 32, a loop having been presented by a looseness in the needle thread 89 adjacent the needle 23 by virtue of the downward movement of the take-up lever 8l, the point 4l of the beak 43 will enter the loop a so that upon continued downward movement of the take-up lever and the rotation of the hook, the needle thread will be disposed with one limb b thereof on the inside of the beak 4I, with the other limb portion c of the needle thread at the base of the thread stop t3, the limb c of the thread being disposed between the beak and the thread guard 4&1. Continued rotation of the hook will eventually locate the limb b in the position shown in Fig. l5, in which position of the needle thread the stitch-forming mechanism is ready to begin its casting operation, which operation takes place upon the continued movement of the hook to a position substantially to the right of a line dividing the hook into two semicircular parts, at which point, the take-up lever, having substantially risen, is in a position by virtue of its continued upward movement, to slide the loop (by reason of tension of the needle thread) off the beak after which the hook, having arrived at its initial position as shown in Fig. 6, continues an idle operation until the needle and take-up lever are moved to a position to present to the beak 4B a second loop. In the foregoing referred to casting operation, the loop encloses the bobbin thread in the usual and conventional manner.

The bobbin and bobbin housing and parts of the bobbin case carrier have portions of the material thereof removed as shown by the slots 80', the purpose of which is to lighten these parts as much as possible and thus prevent their being worn by rubbing or friction due to otherwise excessive weight.

From the foregoing description taken in connection with the accompanying drawings, it is apparent that I have provided a loop-forming mechanism by an arrangement of parts which are substantially simple in construction and which when assembled in the manner shown in the several drawings, will require no lubrication, thus avoiding sliding or soiling of the thread and the material being operated upon, and that any lint or thread-borne parts which might nd lodgement upon the casting flanges of the bobbin case carrier will eventually find lodgement at the base of the casting flange 69 and by reason of the knife edge 83 provided by the ring 36, this lint or thread-borne matter will be ground to minute bits and thrown olf during rotation of the hook.

While I have illustrated and described the preferred form of construction for carrying my invention into effect, this is capable of variation and modification, without departing from the spirit of the invention. I, therefore, do not wish to be limited to the precise details of construction set forth, but desire to avail myself of such variations and modifications as come within the scope of the appended claims.

Having thus described my invention, what I claim as new and desire to protect by Letters Patent is:

1. In combination, a substantially cup-shaped hook member having a sleeve provided with oppositely arranged notches, a bobbin case carrier confined in said hook and provided with a flange, an internal flange on the hook member providing a support for the flange of said carrier, a retainer ring having a vertical wall encircling the hook member and having an inturned horizontal flange extending from the upper edge of said wall and overlying the flange of the carrier, said vertical wall having oppositely arranged notches formed therein, resilient retaining fingers having end portions mounted in said notches of said sleeve and opposite end portions projected into said notches of said vertical wall, and means for connecting the fingers to the hook member.

2. In combination, a substantially cup-shaped hook member having a sleeve provided with oppositely arranged notches, a bobbin case carrier confined in said hook and provided with a flange, an internal flange on the hook member providing a support for the flange of said carrier, a retainer ring having a vertical wall encircling the hook member and having an inturned horizontal flange extending from the upper edge of said wall and overlying the flange of the carrier, said vertical wall having oppositely arranged notches formed therein, resilient retaining fingers having end portions mounted in said notches of said sleeve and opposite end portions projected into said notches of said vertical wall, and means for connecting the lingers to the hook member, said hook member having vertically extending retaining grooves formed therein and said retaining ring having struck-out portions engageable in said retaining grooves.

3. In combination, a vertically extending rotatable shaft, a hook member having a sleeeve mounted on the shaft for rotation therewith, said hook member being substantially cup-shaped and having formed in opposite wall portions thereof vertically extending retaining grooves and provided with an internal flange, a bobbin case carrier having a flange positioned upon the internal flange and having an outwardly and downwardly tapered wall portion, a retaining ring encircling the hook member and having struck-out vportions engaging the retaining grooves and having a horizontally extending flange overlying the ange of the carrier with the periphery of the flange providing a cutting edge confronting the outwardly and downwardly tapered wall of the carrier, and means for connecting the retaining ring to the hook member.

4. In combination, a vertically extending rotatable shaft, a hook member having a sleeve mounted on the shaft for rotation therewith. said hook member being substantially cup-shaped and having formed in opposite wall portions thereof vertically extending retaining grooves and provided with an internal flange, a bobbin case carrier having a flange positioned upon the internal flange and having an outwardly and downwardly tapered wall portion, a retaining ring encircling the hook member and having struck-out portions engaging the retaining grooves and having a horizontally extending flange overlying the flange of the carrier with the periphery of the flange providing a cutting edge confronting the outwardly and downwardly tapered wall of the carrier, and means for yieldably connecting the retainer ring to the hook member.

BERNARD A. SCHMITT.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,299,468 Hohmann Apr. 8, 1919 1,415,268 Smith May 9, 1922 1,504,242 Hohmann Aug. 12, 1924 1,928,590 Grieb Sept. 26, 1933 2,019,284 Wesson Oct. 29, 1935 

